ME-161Introduction to Mechanical Engineering

LEVEL-1, TERM-I

Military Institute of Science & TechnologyDepartment of Mechanical Engineering

Adib Bin RashidCaptInstructor Class CMechanical Engineering Department

Environmental Pollution

Adib Bin RashidCaptInstructor Class CMechanical Engineering Department

MILITARY INSTITUTE OF SCIENCE & TECHNOLOGYDEPARTMENT OF MECHANICAL ENGINEERING

Introduction to Air Pollution

Adib Bin RashidCaptInstructor Class CMechanical Engineering Department

Definition o Air pollution refers to the contamination of the air,

irrespective of indoors or outside.

o A physical, biological or chemical alteration to the air in the atmosphere can be termed as pollution. It occurs when any harmful gases, dust, smoke enters into the atmosphere and makes it difficult for plants, animals and humans to survive as the air becomes dirty.

Types and Sources of Air Pollution

o Air Pollution• Chemicals added to the atmosphere by natural

events or human activities in high enough concentrations to be harmful.

o Two categories• Primary Air Pollutant

• Harmful substance that is emitted directly into the atmosphere

• Secondary Air Pollutant• Harmful substance formed in the atmosphere when a

primary air pollutant reacts with substances normally found in the atmosphere or with other air pollutants

Major Air Pollutants

Causes of Air pollution1. Burning of Fossil Fuels: Sulfur dioxide emitted from the combustion of fossil fuels

like coal, petroleum and other factory combustibles is one the major cause of air pollution.

Pollution emitting from vehicles including trucks, jeeps, cars, trains, airplanes cause immense amount of pollution.

Carbon Monooxide caused by improper or incomplete combustion and generally emitted from vehicles is another major pollutant along with Nitrogen Oxides, that is produced from both natural and man made processes.

Causes of Air pollution

2. Agricultural activities: o Ammonia is a very common by product from

agriculture related activities and is one of the most hazardous gases in the atmosphere.

o Use of insecticides, pesticides and fertilizers in agricultural activities has grown quite a lot. They emit harmful chemicals into the air and can also cause water pollution.

Causes of Air pollution3. Exhaust from factories and industries:o Manufacturing industries release large amount of

carbon monoxide, hydrocarbons, organic compounds, and chemicals into the air thereby depleting the quality of air.

o Manufacturing industries can be found at every corner of the earth and there is no area that has not been affected by it.

o Petroleum refineries also release hydrocarbons and various other chemicals that pollute the air and also cause land pollution.

Causes of Air pollution4. Mining operations:

o Mining is a process where in minerals below the earth are extracted using large equipments.

o During the process dust and chemicals are released in the air causing massive air pollution. This is one of the reason which is responsible for the deteriorating health conditions of workers and nearby residents.

Causes of Air pollution

Causes of Air pollution5. Indoor air pollution:

o Household cleaning products, painting supplies emit toxic chemicals in the air and cause air pollution.

o Suspended particulate matter popular by its acronym SPM, is another cause of pollution. Referring to the particles afloat in the air, SPM is usually caused by dust, combustion etc.

Effects of Air pollution1. Respiratory and heart problems:

o The effects of Air pollution are alarming. They are known to create several respiratory and heart conditions along with Cancer, among other threats to the body.

o Several millions are known to have died due to direct or indirect effects of Air pollution. Children in areas exposed to air pollutants are said to commonly suffer from pneumonia and asthma.

Effects of Air pollution2. Global warming: o Another direct effect is the immediate

alterations that the world is witnessing due to Global warming.

o With increased temperatures world wide, increase in sea levels and melting of ice from colder regions and icebergs, displacement and loss of habitat have already signaled an impending disaster if actions for preservation and normalization aren’t undertaken soon.

Effects of Air pollution3. Acid Rain: o Harmful gases like nitrogen oxides and sulfur

oxides are released into the atmosphere during the burning of fossil fuels.

o When it rains, the water droplets combines with these air pollutants, becomes acidic and then falls on the ground in the form of acid rain. Acid rain can cause great damage to human, animals and crops.

Effects of Air pollution4. Eutrophication: o Eutrophication is a condition where high

amount of nitrogen present in some pollutants gets developed on sea’s surface and turns itself into algae and adversely affect fish, plants and animal species.

o The green colored algae that is present on lakes and ponds is due to presence of this chemical only.

Effects of Air pollution5. Effect on Wildlife: o Just like humans, animals also face some

devastating affects of air pollution. o Toxic chemicals present in the air can force

wildlife species to move to new place and change their habitat. The toxic pollutants deposit over the surface of the water and can also affect sea animals.

Effects of Air pollution6. Depletion of Ozone layer:o Ozone exists in earth’s stratosphere and is

responsible for protecting humans from harmful ultraviolet (UV) rays.

o Earth’s ozone layer is depleting due to the presence of chlorofluorocarbons, hydro chlorofluorocarbons in the atmosphere. As ozone layer will go thin, it will emit harmful rays back on earth and can cause skin and eye related problems. UV rays also have the capability to affect crops.

Effects of Air pollution

Solutions for Air Pollution1. Use public mode of transportation: Encourage people

to use more and more public modes of transportation to reduce pollution. Also, try to make use of car pooling. If you and your colleagues come from the same locality and have same timings you can explore this option to save energy and money.

2. Conserve energy: Switch off fans and lights when you are going out. Large amount of fossil fuels are burnt to produce electricity. You can save the environment from degradation by reducing the amount of fossil fuels to be burned.

Solutions for Air Pollution3. Understand the concept of Reduce, Reuse and

Recycle:o Do not throw away items that are of no use to you. In-fact

reuse them for some other purpose. For e.g. you can use old jars to store cereals or pulses.

4. Emphasis on clean energy resources: o Clean energy technologies like solar, wind and geothermal

are on high these days. Governments of various countries have been providing grants to consumers who are interested in installing solar panels for their home. This will go a long way to curb air pollution.

Solutions for Air Pollution5. Use energy efficient devices: o CFL lights consume less electricity as against their

counterparts. They live longer, consume less electricity, lower electricity bills and also help you to reduce pollution by consuming less energy.

Ozone Depletion in Stratosphereo Ozone thinning/hole

• First identified in 1985 over Antarctica

o Caused by • human-produced

bromine and chlorine containing chemicals

• Ex: CFCs

Ozone Depletion in Stratosphereo Ozone Protects earth from UV radiation

• Part of the electromagnetic spectrum with wavelengths just shorter than visible light

Ozone Depletion in Stratosphereo Hole over Antarctica requires two

conditions:• Sunlight just returning to polar region• Circumpolar vortex- a mass of cold air that

circulates around the southern polar region • Isolates it from the warmer air in the rest of the

planet o Polar stratospheric clouds form

• Enables Cl and Br to destroy ozone

Effects of Ozone Depletiono Higher levels of UV-

radiation hitting the earth• Eye cataracts• Skin cancer (right)• Weakened immunity

o May disrupt ecosystems

o May damage crops and forests

Recovery of Ozone Layero Montreal Protocol (1987)

• Reduction of CFCs• Started using HCFCs (greenhouse gas)

o Phase out of all ozone destroying chemicals is underway globally

o Satellite pictures in 2000 indicated that ozone layer was recovering

o Full recovery will not occur until 2050

Acid Depositiono Sulfur dioxide and nitrogen dioxide emissions

react with water vapor in the atmosphere and form acids that return to the surface as either dry or wet deposition

o pH scale

How Acid Deposition Develops

Effects of Acid Depositiono Declining Aquatic

Animal Populationso Thin-shelled eggs

prevent bird reproduction• Because calcium is

unavailable in acidic soil

o Forest decline• Ex: Black forest in

Germany (50% is destroyed)

Acid Deposition and Forest Decline

Introduction to Water Pollution

Adib Bin RashidCaptInstructor Class CMechanical Engineering Department

Water Pollution

Definition: Any chemical, biological and physical change in water quality that has a harmful effect on living organisms, Human & animals or makes it unusable for agriculture is called Water pollution.

Causes of water pollution1. Sewage: disposing of sewage waste is a major problem 40 percent of

the world's population) don't have proper sanitation (hygienic toilet facilities); although there have been great improvements in securing access to clean water, relatively little progress has been made on improving global sanitation in the last decade. Sewage disposal affects people's immediate environments and leads to water-related illnesses such as diarrhea

sewage contains all kinds of other chemicals, from the pharmaceutical drugs people take to the paper, plastic, and other wastes they flush down their toilets. When people are sick with viruses, the sewage they produce carries those viruses into the environment. It is possible to catch illnesses such as hepatitis, typhoid, and cholera from river and sea water.

Causes of water pollution2. Waste water

o Factories are point sources of water pollution, but quite a lot of water is polluted by ordinary people from nonpoint sources; this is how ordinary water becomes waste water in the first place.

o Virtually everyone pours chemicals of one sort or another down their drains or toilets. Even detergents used in washing machines and dishwashers eventually end up in our rivers and oceans. So do the pesticides we use on our gardens. A lot of toxic pollution also enters waste water from highway runoff. Highways are typically covered with a cocktail of toxic chemicals—everything from spilled fuel and brake fluids to bits of worn tires.

o When it rains, these chemicals wash into drains and rivers.

Causes of water pollution

Causes of water pollution3. Nutrients

Chemical fertilizers used by farmers also add nutrients to the soil, which drain into rivers and seas and add to the fertilizing effect of the sewage. Together, sewage and fertilizers can cause a massive increase in the growth of algae or plankton that overwhelms huge areas of oceans, lakes, or rivers. This is known as a harmful algal bloom.

It is harmful because it removes oxygen from the water that kills other forms of life, leading to what is known as a dead zone. The Gulf of Mexico has one of the world's most spectacular dead zones

Causes of water pollution

4. Chemical waste

o Toxic pollution comes from heavy metals, such as lead, cadmium, and mercury.

o Lead was once commonly used in gasoline (petrol), though its use is now restricted in some countries. Mercury and cadmium are still used in batteries .

o A highly toxic chemical called tributyltin (TBT) was used in paints to protect boats from the ravaging effects of the oceans. Ironically, however, TBT was gradually recognized as a pollutant: boats painted with it were doing as much damage to the oceans as the oceans were doing to the boats.

Causes of water pollution5. Radioactive waste

o Radioactive pollution from nuclear power plants

6. Oil Spilling

o Only 12 percent of the oil that enters the oceans comes from tanker accidents

o Over 70 percent of oil pollution at sea comes from routine shipping and from the oil people pour down drains on land

Causes of water pollution6. Plastics

Plastic is one of the most common materials, used for making virtually every kind of manufactured object from clothing to automobile parts; plastic is light and floats easily so it can travel enormous distances across the oceans; most plastics are not biodegradable (they do not break down naturally in the environment), which means that things like plastic bottle tops can survive in the marine environment for a long time.

Plastics are not toxic in quite the same way as poisonous chemicals, they nevertheless present a major hazard to seabirds, fish, and other marine creatures.

Effects of water Pollution1. Death of aquatic (water) animals

The main problem caused by water pollution is that it kills life that depends on these water bodies. Dead fish, crabs, birds and sea gulls, dolphins, and many other animals often wind up on beaches, killed by pollutants in their habitat (living environment).

2. Disruption of food-chains

Pollution disrupts the natural food chain as well. Pollutants such as lead and cadmium are eaten by tiny animals. Later, these animals are consumed by fish and shellfish, and the food chain continues to be disrupted at all higher levels.

Effects of water Pollution

Effects of water Pollution3. Diseases

Eventually, humans are affected by this process as well. People can get diseases such as hepatitis by eating seafood that has been poisoned. In many poor nations, there is always outbreak of cholera and diseases as a result of poor drinking water treatment from contaminated waters.

4. Destruction of ecosystems

Ecosystem  (the interaction of living things in a place, depending on each other for life) can be severely changed or destroyed by water pollution. Many areas are now being affected by careless human pollution, and this pollution is coming back to hurt humans in many ways.

Effects of water Pollution

Prevention of water pollution.

o Never throw rubbish away anyhow. Always look for the correct waste bin. If there is none around, please take it home and put it in your trash can. This includes places like the beach, riverside and water bodies.

o Use water wisely. Do not keep the tap running when not in use. Also, you can reduce the amount of water you use in washing and bathing. If we all do this, we can significantly prevent water shortages and reduce the amount of dirty water that needs treatment.

o Do not throw chemicals, oils, paints and medicines down the sink drain, or the toilet. In many cities, your local environment office can help with the disposal of medicines and chemicals. Check with your local authorities if there is a chemical disposal plan for local residents.

Prevention of water pollution.

o Buy more environmentally safe cleaning liquids for use at home and other public places. They are less dangerous to the environment.

o If you use chemicals and pesticides for your gardens and farms, be mindful not to overuse pesticides and fertilizers. This will reduce runoffs of the chemical into nearby water sources. Start looking at options of composting and using organic manure instead.

If you live close to a water body, try to plant lots of trees and flowers around your home, so that when it rains, chemicals from your home does not easily drain into the water.